A lexC-113 derivative of Escherichia coli strain WP2 is to be characterized by two dimensional gel electrophoresis and compared to the wild type strain WP2 and lexA, ssb, lex-114, and recA mutant derivatives of WP2. Differences in the proteins synthesized in untreated and cells treated with nalidixic acid or ultraviolet irradiation will be categorized. Strains will also be characterized with regard to recombination proficiency, induction of lambda, induction of colicin El, and mutagenesis. Capacity to perform these processes will be related to the protein composition of the cell as ascertained by two dimensional gel analysis.